For certain applications there are geometrical restrictions on certain portions of the train line to meet specific railway design criteria. For example in gondola cars which are unloaded by rotating the car 180.degree. to a bottom side up position, the rigid portion of the train line is prohibited by an AAR regulation from extending longitudinally beyond the coupler housing striker plate. While the flexible portion of the train line extending between cars is disconnected during rotary dumping, if the rigid portion of the train line were to extend beyond the striker plate, it would interfere with the rotary dumping operation.
Furthermore, because of clearance restrictions caused by end diagonals and the hand brake support there is insufficient space to weld the rigid portion of the train line to the end sill. Thus the rigid portion must be located elsewhere.
Another problem is that a connection must be provided on the inboard side of the rigid portion to allow connection of a bent pipe portion which makes a turn of nearly 180.degree..
The inboard connection also must avoid abutting a wheel when the wheel is in an inwardly rotated position.